Good day, I flashed TWRP lasted 3.2.3-0, LineageOS 14.1 than Gapps as you recomand. All fine, only one thing for moment instead of shutt off is going in recovery mode :).
We are getting offtopic now.
If installation and booting of rom without gapps works then it should not be the rom.
Neither i believe its the twrp 126.96.36.199 (if i remember correctly you were able to flash roms with it)
Did you try latest ope...